In industrial automation technology, analog signals, which are provided by an analog signal output device on an output channel to which the actuator is connected as an external load, are frequently used for controlling actuators. Here, the analog signal output device can have one or a plurality of output channels. The analog signals provided for control essentially divide into current output signals and/or voltage output signals. The current output signals here typically run in a range around 20 mA, optionally also higher, and the voltage output signals in a range around 10V, optionally also higher. For a current signal provided on the output channel, due to a usually very wide burden range to be covered, e.g., between 0 and 550Ω, and the fact that usually alternating high and low loads must be operated, a high leakage power is produced at the driver output of the analog output stage. This is the case especially when very low-impedance loads must be operated within the analog signal output device for providing the desired or needed current output signals.
Consequently, depending on the heat dissipation of the electronic housing used for the analog signal output device, a so-called derating or limiting of the number of current output channels can occur.
Therefore, manufacturers of signal output modules for controlling actuators often specify for the user a small maximum burden to be connected from the outside for analog current outputs in certain modules, in order to limit the maximum power in the analog signal output device or specify for the user the preselection of a given burden range, e.g., between 0 and 300Ω or between 300 and 600Ω.